Control for a ramming hammer with hydraulic drive



Sept. 23, 1969 CORDES ET AL 3,468,222

CONTROL FOR A RAMMING HAMMER WITH HYDRAULIC DRIVE Filed June 30, 1967 3Sheets-Sheet 1 6% Wm M 19 Sept. 23, 1969 H. H. CORDES ET AL 3,453,222

CONTROL FOR A RAMMING HAMMER WITH HYDRAULIC DRIVE Filed June so. 1967 sSheets-Sheet 2 &@W I was Sept. 23, 1969 H, CORDES ETAL 3,468,222

CONTROL FOR A RAMMING HAMMER WITH HYDRAULIC DRIVE Filed June 30, 1967 3Sheets-Sheet :3

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3.5 w a K 32 8 j 445' mum mfaq United States Patent 3,468,222 CONTROLFOR A RAMMING HAMMER WITH HYDRAULIC DRIVE Hugo H. Cordes, 7 Rulantweg,Hamburg 50, Germany, and Hans A. Kroger, Hamburg, Germany; said Kriigerassignor to said Cordes Filed June 30, 1967, Ser. No. 650,411 Claimspriority, application G6ermany, July 6, 1966,

Int. Cl. F61121/04 US. Cl. 91222 8 Claims ABSTRACT OF THE DISCLOSUREBackground of the invention The invention relates to a ram withhydraulic drive. Such rams are used on mobile carrier equipment forsmashing or compacting purposes. They are also employed to drive insheet piles, piles or the like while suspended from a rope or guided bya ram guide.

The object of the invention is to provide a ram of high efficiency withhandy dimensions which is mobile and may be employed in any positioni.e. not only with the working member moving in the vertical direction.

Another object is to provide a ram with a simple and reliable automatichydraulic control which allows for a wide variety of sequence ofstrokes.

The ram comprises a ram block which is movable with respect to the ramhousing and which is connected with the piston of a hydraulic cylinderto which pressure fluid is supplied at a substantially constant ratefrom a pressure fluid pump situated outside the ram.

Summary of the invention .block a greater impact velocity than wouldcorrespond to the quantity of liquid delivered by the pump. Theaccumulators arranged near to the control device reduce the pressurefluctuations in the supply and discharge lines and make available asuflicient quantity of pressure fluid for the control. Thereby, a safeand quick control is made possible. There is also a practically steadysupply and drain flow taking place through the hoses, thus sparing them.

In an especially preferred embodiment of the invention the piston whichis displaceably guided in a working cylinder is connected with the ramblock by means of a hollow piston rod. The volume portion of the workingcylinder through which the piston rod passes, may be steadily connectedto the delivery side of the pump. A hollow control rod adapted to bepushed into the holice low piston rod passes through the upper volumeportion of the working cylinder. The control rod connects at times thehollow space of the piston rod with the upper portion of the workingcylinder by means of openings. Moreover, the hollow control rod connectspermanently the hollow space of the piston rod with a control chamber.This control chamber is open to at least one accumulator cylinder.

The control supported in the ram housing for longitudinal movementtherein. Moreover, the control rod is connected to a valve spoolcontrolling the liquid flow in the ram. The control rod may also bestationarily supported in the ram housing. Then, the valve spool will bearranged separately and moved by a piston projecting into the controlspace. The pressure fluid displaced from the cavity of the piston rodduring the upward movement of the ram block at first pushes back astorage piston arranged in a first storage cylinder, to a stop and thendisplaces the valve spool against the action of a small pistonpressurized by the supply pressure, and/or against a spring.

It may be recommendable to provide the control space with a secondstorage cylinder in which a storage piston designed as a separatingpiston is arranged, the side of which faces away from the control spacewhich is subjected to the supply pressure.

In this manner, at first, a very exact and reliable reversal is effectedby means of the valve spool and thereafter the working piston is stillcapable of moving a further small distance in the same direction whiledisplacing one storage piston.

The ram designed in accordance with the invention may be employed withany angle with respect to the vertical line.

Further improvements and suitable features of the invention areexplained by way of the drawing which shows some embodiments in adiagrammatic view.

Brief description of the drawing FIG. 1 shows a ram for smashing orcompacting operations, which is pivotally connected to the cantilever ofa dredge or other building machinery vehicle, the pressure fluid feedwith constant flow of delivery being shown diagrammatically.

FIG. 2 shows the same ram however with a ram plate having the ram blockbeating thereon, for driving in posts and sheet piles.

FIG. 3 shows a longitudinal sectional view of one embodiment of thecontrol device for automatically controlling the liquid flow within theram housing, the accumulators being shown diagrammatically on a reducedscale.

FIG. 4 shows a longitudinal sectional view taken on another embodimentof the control device.

Description of the preferred embodiments The two control devicesaccording to the invention shown in the FIGS. 3 and 4 essentially differfrom each other in that the embodiment of FIG. 3 makes use of an axiallydisplaceable control rod and the embodiment of FIG. 4 uses a stationaryone. Like reference numerals are used in the figures for correspondingparts.

In accordance with FIGS. 1 and 2 pressure fluid is supplied to thehousing 1 of the ram from a pump 39 after the master valve 40 has beenopened. Said pressure fluid moves the ram block 5 supported in the ramhousing 1 up and down. In this operation, the ram housing (FIG. 1)mounted at a cantilever 37 of a mobile building machine may be guidedover the ground in such a manner that the ram block 5 strikes the groundby its tool 41. The ram housing 1 may also be suspended freely (FIG. 2)or with guidance in a ram guide and put onto a post 35 with anintermediate ram plate 34, the ram block beating onto the post via theram plate 34 and driving the same into the ground.

The pump 39 with the main valve and accessory is arranged on the carrierstand, i.e. the mobile building machine 36. The pressure line 44 of thepump 39 is con nected with the supply line 9 of an automatic hydrauliccontrol device by means of a hose 42, said control device being arrangedin the ram housing 1. In a corresponding manner, a hose 43 is used toconnect return line to the control device return line 16. The ramhousing 1 contains a working cylinder 2 with working piston 3, pistonrod 4 and a ram plate 5 fastened thereat. The piston rod 4 is providedwith a cavity 6 with a hollow plunger rod 7 adapted to be plungedthereinto. The inflowing pressure fluid in the supply line 9 iscontrolled by a valve spool 8, the pressure fluid being capable, forexample, of permanently biasing the underside of the working piston 3via the line 10.. The plunger 7 is provided with bores 11 communicatingthe cavity 6 of the piston rod 4 with the upper volume portion 12 of theworking cylinder 2 with the ram block 5 being near its lowest position.

A compressed-air hydraulic accumulator 13 is inserted in the supply line9 which may be designed as a bubble accumulator with a gas bubble 14 anda bottom valve 15 or also as a piston accumulator.

A compressed-air hydraulic accumulator 17 for low pressure is fitted inthe return line 16. The bore 18 of the plunger rod 7 is permanently incommunication with the control chamber 19 and a storage cylinder 20, thepiston 21 of which is subjected to supply pressure on its other side viathe line 22. A differential piston 24 is fitted in another storagecylinder 23 the large piston surface of which is in communication withthe upper volume portion 12 of the working cylinder 2 via the line 25.The small surface 26 of piston 24 is permanently in communication withthe cavity 6 via the hollow plunger rod 7. This differential piston 24is additionally permanently biased by a psring or by a piston 27subjected to supply pressure. Its stroke is limited by the adjustableabutment member 28. The small piston surface and its annular surface maybe interchanged. Instead of the emerging action of the small piston asshown in the drawing, it is also possible to overrun slots.

FIG. 3 shows the plunger rod 7 rigidly connected with the valve spool 8while movably supported in the ram housing 1. The plunger rod 7 ispressed into a position in which the valve spool 8 fixed thereto causesa lifting movement of the ram block 5, by a spring or a small piston 29subjected to supply pressure. In this operation, the annular area of thedifferential piston 24 is in communication with the cavity 6 of thepiston rod 4 via the passage 30 and the bore 18.

In the embodiment shown in FIG. 4, the plunger rod 7 which may beaxially adjusted by means of an adjusting screw 31, is rigidly connectedwith the ram housing 1. The liquid displaced from the cavity 6 acts onthe piston 32 connected with the valve spool S and, with high pressure,causes the reversal against a permanently effective return force forexample by the spring 33. This spring may also be replaced by a smallpiston 29 subjected to supply pressure as shown in FIG. 3.

The mode of operation is as follows:

The valve spool 8 is initially in a position effective to cause thelifting movement of the ram block 5 (FIG. 3). Before lifting, the bores11 are open so that a balance may take place between the volumes 12 and6. During the lifting movement, these bores 11 become blocked by thepiston 3. The liquid displaced from the volume 6 flows now through theupper bores of the plunger rod 7 and first displaces the differentialpiston 24 against the force of the small piston 27 to the abutmentmember 28. Upon further increase of the pressure within volume 6, untilthe upward force acting on plunger 7 exceeds the 4 downward force onpiston 29, the plunger 7 will be moved upwardly shifting valve 8 to itsupper position. This occurs because the small piston 29 has a smallerdiameter than the plunger rod 7.

In accordance with FIG. 4, the reversal is effected in that a liquidpressure smaller than the supply pressure and acting on the piston 32,suffices to revert the valve spool 8 against the force of the spring 33.Instead of the spring 33, asmall piston subjected to the supply pressureand having a diameter smaller than that of the piston 32 may effect thereturn movement.

After reversal of valve 8, the ram block 5 will continue its upwardmovement due to inertia. Thereby, pressure liquid is pressed into theaccumulator 13, and liquid is displaced from the cavity 6 into thestorage cylinder 20. This liquid moves the piston 21 against the supplypressure and the displaced liquid is pressed into the accumulator 13.

The ram 3 will stop its upward movement upon forcing fluid intoaccumulator 13, and as the supply fluid communicates with chamber 12 andexhaust passage 16 is blocked the ram 3 is forced downward. During thelowering movement, the piston 21 returns into its starting position. Thedifferential piston 24 returns only until the small piston surface 26enters into its cylinder bore because the liquid trapped in the annularspace cannot escape through the channel 30. Now, the reversal into theposition causing the lifting movement is effected, namely by the smallpiston 29 in accordance with FIG. 3 and by the spring 33 in accordancewith FIG. 4, because the liquid pressure in the cavity 6 drops. Theshifting of the plunger 7 under the influence of the small piston 29,and the shifting of the piston 32 under the influence of the spring 33in the embodiment of FIG. 4, results from the diflerential pressureacting upon these small pistons due to the pressure drop occurring incavity 6. This pressure drop in cavity 6 results from the fact that lessfluid flows into cavity 6 from the chamber between pistons 24 and 26than was previously accepted from cavity 6, due to the stopping of thepiston 24 at the location determined by the entering of the piston 26into its cylindrical bore. Thus, the introduction of a lesser amount offluid into cavity 6 results in a lowering of its pressure permitting theshifting of the plunger 7, or the piston 32, before the initial positionof the ram block 3 is reached. After reversal has been effected, theannular space of the differential piston 24 is drained via the now openline 30 into the cavity 6 and the bores 11 are opened.

The upper point of reversal may be varied by adjusting the abutmentmember 28.

In accordance with FIG. 4 the plunger rod 7 can be axially displaced bymeans of the adjusting screws 31 whereby the lower point of reversal isadjusted.

What we claim is:

1. A double action ram adapted to be supplied at a substantiallyconstant rate of delivery of pressurized medium comprising, incombination, a ram housing having a cylinder defined therein, a pistonmovably mounted in said cylinder and including first and secondoppositely related faces, said first face having a smaller area thansaid second face, a ram block mounted on said piston, an axiallyextending chamber defined in said piston, a tubular plunger mounted onsaid housing located within said chamber and slidably sealed withrespect thereto and having an inlet communicating with said chamber andan outlet, a pressurized fluid supply conduit communicating with saidfirst piston face, a passage defined in said housing between said pistonsecond face and said supply conduit, a valve within said passagecontrolling fluid flow therethrough, piston reversing control meanscommunicating with said plunger sensing the pressure within said pistonchamber as said piston is axially translated relative to said plungerselectively positioning said valve, and an exhaust conduit selectivelycommunicating with said piston second face.

2. In a double-acting ram as in claim 1 wherein said piston reversingcontrol means includes a differential pressure piston mounted in saidhousing in communication with said plunger outlet.

3. In a double-acting ram as in claim 2, biasing means biasing saiddifferential pressure piston.

4. In a double-acting ram as in claim 1 wherein said valve is mounted onsaid plunger.

5. In a double-acting ram as in claim 4, means mounting said plunger onsaid housing for limited axial movement relative thereto.

6. In a double-acting ram as in claim 1, a control piston slidablymounted in said housing communicating with said plunger, said valvebeing mounted on said control piston.

7. In a double-acting ram as in claim 6, means adjustably fixing saidplunger to said housing.

8. In a double-acting ram as in claim 1, a first compressed gasaccumulator communicating with said supply conduit and a secondcompressed gas accumulator communicating with said exhaust conduit.

References Cited UNITED STATES PATENTS 2,182,059 12/1939 Schwartz 60-513,322,038 5/1967 Dobson 9130O 3,353,352 11/1967 Gardner 6051 FOREIGNPATENTS 845,069 8/1960 Great Britain.

15 PAUL E. MASLOUSKY, Primary Examiner US. Cl. X.R.

